Sura ppt final

1. •The Aim of this research project is to synthesize a very lightweight
polymer based carbon nanotube (CNT) composites with high strength,
high thermal and electrical conductivity, which finds its application across
various fields
•The uniqueness of this composite will be aligning the well dispersed
carbon nanotubes in a polymer matrix to achieve the most effective
directional properties.
Alignment of a PVDF-CNT Nano-Composite by
applying AC Electric Field

2. Composites
• Combining materials with the objective of getting a more desirable combination of
properties
• Component of composites
Matrix
reinforcement
interface
• Here we are trying to obtain properties of polymer (flexibility & weight of a polymer) plus
the properties of CNT(conductivity, strength)

3. PVDF and Its Properties
• PVDF is a synthetic semi crystalline(about 55%) long chain
polymer with the repeating unit of —CF2—CH2— .
• These are less dense thermoplastic fluoro polymer which
have high resistant to chemical corrosion, heat and have low
thermal conductivity.
• The crystalline structure of PVDF can be classified into four
types α,β,γ and δ forms. Among these beta form provide
best ferroelectric properties.

4. • It shows much better piezoelectric and pyroelectric properties
as compared to other organic materials and has considerably
high dielectric strength and high sensitivity to mechanical load.
• PVDF thin films are orthotropic in nature as their mechanical
response depends strongly on direction of stress applied.
•It behaves as ductile polymer if stress is applied perpendicular to the
polymer chain
•And as brittle if stress is applied in parallel to polymer chain

5. CNT and Its Properties
• Due to their unique structure, CNTs possess many remarkable
properties, such as high specific surface area, high aspect ratio,
remarkable high electrical and thermal conductivity, chemical stability.
•They have very strong and flexible molecular material because of C-C
covalent bonding and seamless hexagonal network architecture.
•Prior to CNT, diamond was the best thermal conductor. CNT have
now been shown to have a thermal conductivity at least twice that of
diamond.

6. •The electrical properties of carbon nanotubes depend on the tube types.
While MWNTs are generally all metallic, SWNTs can be either metallic or
semiconducting, depending on the structure parameters such as the
chirality. For metallic single-walled carbon nanotubes, the electric
conductivity is on the order of 104 S/cm.
•In terms of mechanical properties, carbon nanotubes are among the
strongest and most resilient materials known in nature. The tensile
strength of carbon nanotubes is about a hundred times that of steel. So
they can tolerate large strains before mechanical failure.

8. Process for the fabrication of Nano-
Composite :
1). Dispersion of CNTs in Polymer Matrix.
2). Alignment of CNTs in Polymer.

9. Dispersion Techniques:
• To maximize the advantage of CNTs as effective reinforcements in high
strength composites, proper techniques for the dispersion of CNTs in
polymer matrices should be used. Such as
 Optimum physical blending
 In situ polymerization
 Chemical fictionalization and
 Sonication
• Out of these we are going to use Sonication which is a powerful
technique to promote the dispersion of carbon nanotubes (CNTs) and
enhance their solubility, this is necessary for CNT applications, especially
in the biochemical and biomedical fields.

10. Techniques for the Alignment of CNTs:​
2) Perpendicular Aligned CNT can be
grown on substrate surface using High
Frequency Microwave Plasma enhanced
chemical vapour deposition(MPECVD)
1)CNT can be aligned vertically on the
polymeric membrane substrate by using
HPPO(Hot Press combined with Peel off)
technique.

11. 3) CNT can also aligned by using the
magnetic field which reorient them in
direction parallel to the magnetic field.
4) SWCNT can be aligned using an AC
Electric Field , where the substrates is
placed between the gold electrodes for
15 min and then were taken out and dried
in.

12. SEM images of the SWCNT samples aligned in different conditions:
(a) Aligned by applying an ac electric field
with a frequency of 5MHz and a voltage of 10
V peak to peak.
(b) Aligned by applying an ac
electric field with a frequency of 5 MHz and
a voltage of 6 V peak to peak.
(c) Aligned by applying an ac electric field with a
frequency of 500 Hz and a voltage of 10 V peak
to peak.
•Therefore the concentration of the aligned SWCNTs is dependent on the magnitude of the electric field.
When the magnitude of the electric field was decreased, there were fewer carbon nanotubes attracted in
the gaps.
•Also the degree of the alignment is apparently depending on the frequency of the ac electric field as the
degree of alignment of carbon nanotubes reduce gradually with the decrease in the frequency of the
electric field.

13. Possible properties of CNT/PVDF composite
• High thermal and electrical conductivity if alignment
obtained
• High strength
• Lightweight
• High hardness
• Might show Remote Joule heating effect

14. Polymer/CNT nanocomposites potential
applications:
• MECHANICAL may find use in structural material, aerospace and terrestrial applications.
• THERMAL as printed circuit boards, connectors, thermal interface materials, heat sinks, lids
and housings, and high-performance thermal management from satellite structures down to
electronic device packaging.
• ELECTRICAL transparent conductive coatings, electrostatic dissipation, electrostatic
painting, electrochemical actuation, electromagnetic interference shielding (EMI), wave
absorption, electronic packaging, self-regulating heater, PTC resistors, and Ultra capacitors
etc.
• OPTICAL could be used to protect human eyes, optical elements, optical sensors and optical
switching.
• SUPER-HYDROPHOBIC super-hydrophobic surfaces like for coatings, textiles, non-wetting
liquid transfer, etc.

15. Characterization/Evaluation of the Composite
• The morphology of the composite and distribution of CNTs in the matrix would be evaluated
through scanning electron microscopy. Infra Red Spectroscopy would also be used to
understand bonding behavior at CNT-polymer interface.
• The mechanical properties of the composite will be investigated in terms of elastic
modulus, tensile strength and toughness along and across the alignment direction.
Comparison would also be made with only polymer and the randomly reinforced polymer to
understand the effect of CNT addition and its alignment, respectively, on mechanical
properties of the composite structure.
• Similar characterization would also be carried out for the electrical conductivity of the
structure.
With different composition of CNTs in composite we will be studying
1. Morphology and bonding at Interface
2. Mechanical Properties
3. Electrical Conductivities